1. Field of the Invention
The present invention relates to a simple examination method of infection with Helicobacter pylori (hereinafter may also be abbreviated as "H.p.") which is a bacillus and may present in gastric mucosa, and a device therefor. According to the invention, the information on H.p.-infection and the activity of H.p. at the time of examination can be easily obtained.
2. Related Arts
Because of the strongly acidic environment of the inside of the stomach, the gastric cavity had been considered unsuitable for the survival of bacilli since old times; however, about 100 years ago, the existence of spiral bacillus was observed and reported. The bacilli were formally discovered in the second half of the 1970's. In 1983, the bacilli were firstly isolated from gastric mucosa by Waren et al., and was named at first as "Campylobacter pyloridis, because it morphologically and biologically resembled Campylobacter which is one or Salmonella enteritidis, in addition to the fact that it was isolated from gastric antral mucosa in the vicinity of the pylorus. Later, the name was once changed to Campylobacter pylori. The genetic name has been changed to "Helicobacter" based on its form, since the difference from Campylobacter became clear in 1989.
Continuous effort has been made investigating the correlation between H.p. and diseases of the upper alimentary tract even since the bacilli were isolated at a high rate by Marshall et al. From patients with gastric ulcer, duodenal ulcer or chronic gastritis in 1984, and the association between the presence of the bacilli and these diseases has been reported ["The lancet", No. 8390, pages 1311-1314 (June 1984)].
According to the subsequent study results, although the correlation has not been proved, H.p. are regarded as an important factor in the etiology of cancer of the stomach; therefore, the diagnosis of H.p.-infection has an important clinical significance to the treatment for the aforesaid diseases.
At the present time, such methods of examining H.p. as a microscopic examination method on gastric mucosa, a cultivation method of gastric mucosa tissue, and a rapid urease test on gastric mucosa tissue have been in the art, but all of the conventional methods need endoscopy which requires advanced technical skill or expertise and is too heavy a burden for patients; therefore, the clinical application of these methods is limited.
On the other hand, a method, which is now under consideration, for measuring anti-H.p. antibodies in blood or sputum cannot be applied for obtaining information on the present state of H.p.-infection, because of the time lag between H.p.-infection and appearance of the antibodies, or between H.p.-elimination and disappearance of the antibodies.
There is a .sup.13 C-breath test as the method for obtaining informations on the present state of H.p.-infection without causing pain to the patients, but the clinical application thereof is also limited, because of the necessity of a radioisotope in combination with a large-sized and expensive apparatus, in addition to the inability of speeding up the operation of the apparatus in connection with the transportation of the specimen.
We have just found U.S. Pat. No. 4,947,861 (issued Aug. 14, 1990) disclosing a diagnosis of H.p. infection. In the patent specification (columns 2-4), Hamilton teaches a fact that ammonia could not be detected in expired alveolar air with a conventional apparatus, although the detection has been made based on theory that if urea is administered to a person infected with H.p., at least some portion of ammonia generated by the activity of H.p. is absorbed into the blood stream, passes through the liver without being broken down there, and is delivered to expired air at the alveoli of the lungs, but can be detected with the conventional apparatus, if a breath sample is treated by a desiccant material such as sodium hydroxide to absorb therein H.sub.2 O and CO.sub.2 in the sample breath and collect the dried breath, prior to the detection. however, he does not disclose any actual Example on diagnosis of H.p.-infection. We think this means that even if ammonia in the breath sample can be detected, an application of the method for the actual diagnosis is quite difficult or impossible from the view point of sensitivity, since almost all part of ammonia absorbed into the blood stream will be broken down by the liver and only a trace amount thereof shall appear in the breath sample, as stated also by him (line 24 in column 3).